Liquid-repellant covering layer and method for the manufacture of such covering layer

Abstract: Liquid-repellant covering layer, characterized in that it consists of at least a compact layer (2) which is formed by a mass of fibers (3) and a clay product (4).

Description: This invention relates to a liquid-repellant covering layer and a method for the manufacture of such covering layer. It is known that clay mats can be used for a liquid-tight covering. Such clay mats, above all, are used in water basins, channels and such as a seal between the water and the soil; as a seal between the water and the supporting structures in roof gardens, cellars and such; as a seal for waste deposits in order to prevent the infiltration of rain water and/or to prevent the penetration of liquids into the soil underneath; as well as a cover for industrial installations, such as tank plants, gas stations, storage areas, production units and such, also in order to prevent the penetration of liquids into the soil underneath. The existing clay mats usually are composed of a homogenous layer of clay which, at both sides, is provided with a layer of geotextile. This known embodiment shows the disadvantages that the clay can shift easily between or be released from the textile layers, which may lead to the forming of micro-cracks or breaches through which liquid can penetrate, and that the clay, when cutting such clay mats, can drop off at the edges from between the textile layers. It is also obvious that these clay mats are not very apt for vertical installation or installation onto a slope. Another known embodiment is composed of a membrane (for example, polyethylene foil or similar) on which bentonite is adhered, which is provided at the opposite side with a protective fabric or not. Also in this case, the bentonite may easily be released, and the foil is very sensitive to perforation. Further, EP-A-0 491 453 discloses a covering layer which is formed by a clay product which is reinforced by means of fibers. According to EP-A-0 491 453, the layer is manufactured according to a method in which all fibers are spread out in a welldefined direction, clay is applied between the fibers and the whole is needled. Although during needling a number of fibers is brought in another direction, the practice has shown that almost all fibers remain orientated in the said direction, resulting in the disadvantage that the efficiency of the obtained fiber reinforcement is only small. The present invention aims at a covering layer which does not show said disadvantage, thus providing a covering layer having a maximum strength in all directions. Hereto, the invention relates to a liquid-repellant covering layer, comprising a compact layer which is formed by a mass of fibers and a clay product, characterized in that the liquid repellent covering layer is composed of a plurality of said compact layers which are applied crosswise over each other, whereby these layers are mutually connected. In the most preferred embodiment, the said layer is provided with a coating and/or an armouring in order to further increase the mechanical properties of the covering layer. The invention also relates to a method for the manufacture of such covering layer, characterized in that it comprises the steps of forming a mass of fibers; processing the mass of fibers and a clay product into each other; and compressing the whole to a compact layer, whereafter those layers are applied crosswise over each other and mutually connected. In this way, an especially coherent covering layer is obtained. In order to optimally process the clay product between the fibers, one starts from an existing layer of fibers which is stretched into a mass of fibers having an open structure, or it is started from an existing mass of fibers having an open structure, and subsequently the clay product is brought between the fibers, preferably by injecting, spreading or blowing it into the mass of fibers in the form of particles or powder. According to the invention, one may also start with an open-structured mass of fibers which, in the first place, is produced by the stacking of loose fibers, whereby the clay can also be brought in between by means of spreading, injecting or blowing. In order to better show the characteristics according to the invention, hereafter some preferred embodiments are described, as examples without any restrictive character, with reference to the enclosed drawings, wherein: figure 1 represents a rolled-up layer according to the invention; figure 2, on a larger scale, represents a cross-section according to line II-II in figure 1; figure 3 represents a step of a method for the manufacture of such layer; figure 4 represents a variant of a layer according to the invention; figure 5 represents an further embodiment of the invention during its composition. Figures 1 and 2, represent a covering layer 1, having the characteristic that it at least consists of a compact layer 2 which is formed of a mass of fibers 3 and a clay product 4, processed in between. For the fibers 3, preferably glass and/or plastic fibers are used, however, to this end it is not excluded to apply other fibers, too, for example natural fibers. Preferably, use is made of a needled or nailed mass of fibers. Although the said clay product 4 preferably consists of pure bentonite, it is not excluded to use a mixture based on clay, in other words, clay mixed with other materials. The layer 1 is preferably manufactured by subsequently forming a mass of fibers; processing the mass of fibers and the clay product 4 into each other; and compressing the whole to a compact layer 2. As represented in figure 2, hereby the mass of fibers and the clay product 4 can be processed into each other by stretching an existing layer of fibers until a mass of fibers 5, having an open structure, is obtained, and subsequently applying the clay product 4 between the fibers 3. It is obvious that hereby one can also start with an existing layer of fibers or mass of fibers which itself already presents an open structure. As further represented in figure 2, the application of the clay product between the fibers 3 may be performed by injecting, spreading or blowing the clay product 4 into the mass of fibers 5, in the form of particles such as clay pellets or clay powder. According to a variant, the mass of fibers 5 may also be formed by spreading the fibers over each other and injecting and/or spreading the clay particles herein. The compression of the whole to a compact layer 2 can be performed in any manner. Preferably, this is realized by applying the whole to be compressed between two pressure plates or by rolling it flat and/or needling or nailing (needle punching) it. As represented in figure 4, the said layer 2 may be provided with a coating 6, preferably at both sides thereof. This coating 6 preferably consists of a textile layer, such as geotextile or a geomembrane. The attachment of the coating 6 at the layer 2 may be performed by glueing, needling, stitching, thermic welding or by means of a combination of these techniques. Hereby, it is remarked that the fibers 3 which reach up to the outer side of the layer 2, allow an optimum adherence between the coating 6 and the layer 2. According to a not represented variant, the covering layer 1 is provided with an armouring, for example of geotextile and/or metal and/or plastic, in order to increase its strength. According to the invention the covering layer 1 is composed of several compact layers 2 which are applied on top of each other, with or without the inclusion of other layers. As schematically shown in figure 5, the compact layers 2 are placed crosswise over each other. As the compact layers 2 mostly show a greater strength in one direction than in the other direction, the crosswise placement on top of each other offers a maximum strength in all directions on the finally obtained covering layer 1. As shown in figure 5, the crosswise structure hereby can be formed by unrolling compact layers 2 from two rolls 7 and 8 and applying them in a zigzag movement alternatingly on top of each other. This process can also be performed successively, first in one direction and then in the other and so on. During this process, the spreading or injection of clay pellets between the structures, unrolled in a zigzag manner, is possible. The mutual securing of the composing layers may also be realized by means of the aforementioned techniques. The present invention is in no way limited to the embodiments described as examples and shown in the figures, however, such liquid-repellant covering layer 1 and the method for the manufacture thereof can be realized according to different variants without leaving the scope of the invention, as defined in the claims.

Claims: Liquid-repellant covering layer, comprising a compact layer (2) which is formed by a mass of fibers (3) and a clay product (4), characterized in that the liquid repellent covering layer is composed of a plurality of said compact layers (2) which are applied crosswise over each other, whereby these layers (2) are mutually connected. Liquid-repellant covering layer according to claim 1, characterized in that the clay product (4) consists of bentonite. Liquid-repellant covering layer according to claim 1 or 2, characterized in that the fibers (3) consist of glass fibers and/or plastic fibers. Liquid-repellant covering layer according to any of the previous claims, characterized in that the fibers (3) consist of a nailed or needled mass of fibers. Liquid-repellant covering layer according to any of the previous claims, characterized in that the said compact layer (2) at least at one side is provided with a coating (6). Liquid-repellant covering layer according to claim 5, characterized in that the compact layer (2) at both sides is provided with a coating (6). Liquid-repellant covering layer according to claim 5 or 6, characterized in that the coating (6) consists of a geotextile. Liquid-repellant covering layer according to claim 6, characterized in that the coating (6) consists of a geomembrane. Liquid-repellant covering layer according to any of the previous claims, characterized in that it is provided with an armouring. Liquid-repellant covering layer according to claim 9, characterized in that the armouring consists of metal. Liquid-repellant covering layer according to claim 9, characterized in that the armouring consists of plastic. Liquid-repellant covering layer according to any of the previous claims, characterized in that the composing layers are mutually connected by means of one of the following techniques or a combination of these techniques: glueing, needling or nailing, stitching, and thermic welding. Method for the manufacture of a liquid-repellant covering layer as described in claim 1, characterized in that it comprises the steps of forming a mass of fibers; processing of the mass of fibers and a clay product (4) into each other; and compressing the whole to a compact layer (2), whereafter those layers are applied crosswise over each other and mutually connected. Method according to claim 13, characterized in that the mass of fibers and the clay product (4) are processed into each other by stretching an existing layer of fibers up to a mass of fibers (5) having an open structure and by applying the clay product (4) in between the fibers (3). Method according to claim 13, characterized in that the mass of fibers is formed by spreading, injecting or blowing fibers over each other. Method according to claim 13, 14 or 15, characterized in that the clay product (4) is applied in between the fibers (3) by injecting it into the mass of fibers (5) in the form of particles or powder. Method according to claim 13, 14 or 15, characterized in that the clay product (4) is applied in between the fibers (3) by spreading it in into the mass of fibers (5) in the form of particles or powder.

Inventors: CLATWORTHY JOHN, CLATWORTHY, JOHN
Applicants: E E C NAAMLOZE VENNOOTSCHAP, E.E.C., NAAMLOZE VENNOOTSCHAP
Application year: 1994
Main classification: E02D31
IPC codes: E02D31